These studies concern the examination of the structure and replication of the mycoplasma chromosome and the description of the molecular events in the replication of the subcellular organelles of Mycoplasma gallisepticum. The chromosome experiments involve the biochemical and biophysical characterization of isolated mycoplasma folded chromosomes. The M. gallisepticum studies are utilizing cytochalasin B as a specific inhibitor of certain steps in the cell cycle, to examine the regulation and assembly of subcellular organelles in the cell cycle. BIBLIOGRAPHIC REFERENCES: Das, J., J.A. Nowak, and J. Maniloff (1977). Host cell and ultraviolet reactivation of ultraviolet-irradiated mycoplasmaviruses. J. Bacteriol., in press. Ghosh, A., J. Das, and J. Maniloff (1977). Lack of deoxyribonucleic acid repair mechanisms in Mycoplasma gallisepticum, in press.